HomeWinBuzzer NewsMicrosoft Exchange Online Users to Be Throttled When Reaching Upper Mail Limit

Microsoft Exchange Online Users to Be Throttled When Reaching Upper Mail Limit

Microsoft says it will more strictly police the upper limit of Microsoft Exchange Online emails, with the threshold at 3,600 per hour.


says it is going to take a stricter position on the number of emails that Online can accept. The company's email hosting service, which underpins the Outlook experience, will start enforcing its upper limit for messages received starting this April.

It is worth noting Microsoft Exchange Online has always had an upper limit. This is a cap on the number of emails someone can receive. This upper limit only really bothers so-called “hot recipients”, users who receive thousands of emails each hour.

That upper limit is 3,600 but Microsoft has never really been strict about enforcing it. In other words, recipients were receiving over the upper limit without Microsoft stopping them. The company now says that will change.

In an effort to optimize Exchange performance across inboxes and deliver a unified capacity, the company will start enforcing that 3,600 emails per hour limit. According to Microsoft, mailboxes that pass this limit often see service disruptions for themselves and others.

New Method

To prevent this, Microsoft will throttle tenants receiving over the upper limit. Emails to mailboxes will get a non-delivery report if it is over the limit. Because the limit is hourly, Microsoft will continue to reset the threshold automatically each hour.

The company says the changes reflects in the following products:

  • Business Basic
  • Microsoft 365 Business Standard Office
  • Enterprise E1
  • Office 365 Enterprise E3
  • Enterprise E5
  • Office 365 Enterprise F3

Microsoft new throttle and limit will come into action this April. The company says admins should be more wary of the number of mails they are receiving across mailboxes, especially if there are hot recipients.

To ease customers into the change, Microsoft will start the threshold above 3,600 and slowly reduce to help organizations adapt.

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Luke Jones
Luke Jones
Luke has been writing about all things tech for more than five years. He is following Microsoft closely to bring you the latest news about Windows, Office, Azure, Skype, HoloLens and all the rest of their products.

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